The field of the invention is the diagnosis and treatment of muscle injuries associated with pain and stiffness.
It is estimated that up to 20% of the adult population in the United States suffers from chronic and recurrent muscle pain. There is currently no FDA-approved or proven effective treatment for these conditions. Treatments now used give only limited temporary relief.
Chronic and recurring muscle pain is a neuromuscular abnormality typically following a strain injury, and manifested by what has been termed trigger point (TrP) phenomena. As used herein, trigger point means a localized area of tenderness within a muscle associated with spontaneous electromyographic (EMG) activity. Thus, a trigger point is a location of spontaneous EMG activity within a muscle associated with pain. Trigger points may be within muscle spindles. TrPs can be objectively diagnosed by identification of spontaneous EMG activity in a trigger point while adjacent muscle fibers are electromyographically quiet. Once the trigger point EMG activity is identified, chronic and recurrent muscle pain associated with this localized EMG activity can be treated through the use of medications including sympathetic blocking agents, as described in U.S. Pat. No. 5,513,661, incorporated herein by reference. This patent describes a method of identifying trigger points in muscle associated with a characteristic spontaneous EMG activity. The activity is then blocked by injecting adrenergic blocking agents. The methods of diagnosis and treatment described in U.S. Pat. No. 5,513,661 involves simultaneously measuring both the trigger point activity and the EMG activity adjacent to the trigger point to determine whether the observed trigger point EMG activity is spontaneous localized, and not due to other phenomena such as voluntary contraction. To effectively block sympathetic activity at a trigger point, it is desirable to localize the trigger point as precisely as possible. For effective treatment, the blocking agent should be delivered precisely at the trigger point. Accordingly, there remains a need for a device for simultaneously locating and treating TrP EMG activity.
To these ends, in a first aspect of the invention, an EMG device for diagnosing chronic and recurrent muscle pain preferably integrates two or more active EMG electrodes and an EMG reference electrode.
In a second aspect of the invention, an EMG device for treating chronic and recurrent muscle pain integrates two or more active EMG electrodes and a reference electrode and includes a drug delivery system.
In a third aspect of the invention, a system is provided for analyzing the level of spontaneous EMG activity in trigger points and adjacent muscle tissue.
Other objects and advantages will appear as well hereinafter.